This invention relates in general to wireless communication systems, and more specifically to a method and apparatus in a wireless messaging system for estimating and using required delivery parameters to meet a target transmission reliability.
Information services messages (IS) are becoming increasingly important in wireless messaging systems. Such messages add to the attractiveness of wireless messaging and may become a major source of revenue. Users who pay for IS messages will expect reasonable reliability of delivery.
A potential problem with the delivery reliability is created by virtue of the fact that IS messages are normally sent as one-way group-call messages, which typically are received simultaneously by a large number of messaging units. The large number of messaging units makes an individual acknowledgment from each unit impracticable, even when the unit has two-way transmission capability. The lack of an acknowledgment makes it impossible to be certain that an IS message has been delivered reliably to all intended recipients.
Delivery reliability can vary widely among zones and subzones of a messaging system. Many two-way systems are configured for reliable two-way delivery and can retry an outbound message in response to a missing or negative acknowledgment. One-way delivery in such systems can be somewhat compromised. This implies that one-way IS message fragments may have to be repeated. A prior art technique has been to use a static controller configuration which sets a maximum fragment size and a minimum repeat count for IS messages. That technique is course, because it does not take into account the varying message lengths, varying transmission rates, varying reliability of zones and subzones, different reliability requirements for different messages, and the variation of reliability with time.
Thus, what is needed is a method and apparatus in a wireless messaging system that can provide an automated technique for taking these variations and differences into account in order to achieve a specified message delivery reliability. Preferably, the method and apparatus will achieve its objective with a minimum of overhead.
An aspect of the present invention is a method in a wireless messaging system for estimating and using required delivery parameters to meet a target transmission reliability. The method comprises the steps of monitoring delivery of two-way outbound messages to a plurality of portable messaging units, and recording reliability statistics for the two-way outbound messages as a function of delivery parameters. The method further comprises the steps of determining the target transmission reliability for sending a message; and estimating, from the reliability statistics, the required delivery parameters for sending the message at the target transmission reliability. The method also includes the step of transmitting the message in accordance with the required delivery parameters.
Another aspect of the present invention is a controller in a wireless messaging system for estimating and using required delivery parameters to meet a target transmission reliability. The controller comprises a network interface for receiving a message for transmission, and a processing system coupled to the network interface for processing the message. The controller further comprises a base station interface coupled to the processing system for controlling a base station to transmit the message. The processing system is programmed to monitor delivery of two-way outbound messages to a plurality of portable messaging units, and to record reliability statistics for the two-way outbound messages as a function of delivery parameters. The processing system is further programmed to determine the target transmission reliability for sending the message; and to estimate, from the reliability statistics, the required delivery parameters for sending the message at the target transmission reliability. The processing system is also programmed to transmit the message in accordance with the required delivery parameters.